Internal-combustion percussive tool



March Z0, 1951 c. A. HlRscHBERG 2,545,999

INTERNAL-COMBUSTION PERCUSSIVE TOOL Filed July 2l, 1948 4 Sheets-Sheet 2 f/ QV gw/ milillm March 20, 1951 c. A. HlRsc'HBERG v 2,545,999

INTERNAL-COMBUSTION PERCUSSIVE TOOL Filed July 21, 1948 4 Sheets-Sheet 3 March 2.0, 1951 c. A. HIRSCHBERG 2,545,999

, INTERNAL-COMBUSTION PERCUSSIVE TOOL Filed Julsr 2l, 1948 4 Sheets-Sheet 4 l INVENTR. (h/45s Marax/55H@ Patented Mar. 20, y 1951 UNITED STATES PATENT -OFFICE lINTERNL-CMBUSTIONLPERCUS SIVE TOOL Charles `A. Hirschberg, Mountain Lakes, N. J

Application July21, 1948, Serial No. 39.902 f (Cl. 12g-7) .13 Claims.

The inventionhere disclosed-relates lto percussive apparatus. such yas rock drills; A pavement breakers, pile drivers, tampers and thelike.

Objectsl ofv the invention are to providea-pparatus of this general nature'whichl will'zutilize the advantageous features of aninternal combustion engine but will have a free hammering action, without the restrictions of: a rigid connection betweenthe hammer and the cycle controlling; portions of the apparatus.

Special objects also are to'provide an` internal combustion type of powerv hammerwhich- -w-ill consist v`of but vfew sturdy-parts-freeof` compli- .cated valvemechanisms andthe like.

Aiurther Objectis to provide full, .automatic lubrication ofall-.operating parts. K

Other desirable objectives and ethe novel. featuresof invention by whichall objectives are. at-

tained are set forth or willappearfin the course of the following'specication.

The drawings accompanying and "formingv part of the specification illustrate the structure .and operation of a present commercial embodiment of the invention.' This disclosure, however, is

Vprimarily by way ofqillustration, it being contemplated that many 'changes and'modications are possible, all within thetrue intent and broad scope of the invention as hereinafter dened and claimed.

Figs. 1 and 2 inthe drawings "are longitudinal `sectional views of one ofthe power hammers,

taken on planes at rightaifigles=` to eachother;

Fig. v3 is an enlarged broken 'sectionaldetail' illustrating construction of the outlet and-inlet valves in thehead of the inner, compressor piston;

Figs, 4 'and arebroken horizontal sectional .views oi the outlet andinlet valves las on substantially'the planes of lines 4;-4 and 5;-5 of Fig". v3;y

Figs. 61and 7 are brokenpvertical' sectional details of the outlet and inletrvalves as lon substantially the planes of lines-6 3 and 1--1 of Figs.

Il and 5, respectively;

Figs. 8 and 9 are cross sectional views-of the machine as on substantially the planes of vlines 3-.8 and 9--9 of Figs. 1 and 2, respectively;

Figs. 10 to 15 are sectional and partly'diagrammatic'views illustrating acycle of operation of the machine.

As shownin Figsrland 2,:thermachineconsists inthe main of a working-cylinder 2G, a free piston 2l operating therein, subjected to explosion forces and delivering power impulsesand-a crank connected piston 22 within the power piston cooperating with the latter-to providea lcompression coupling betweenfthetwopistons and to accomplishthe .valvingfunctions requiredL for operation of the machine as anrinternal combustionengine.

The power pistonis` shownras carrying a ham- Y 2 .mer 23 at itsslower end for striking the steel 24 .retained intheguide 25 at rthelower end of the cylinder.

In the portable form of machine illustrated, the cylinder is equipped with ysuitable handles v26 which may carry the controls `for the engine.

The inner, fixed stroke piston is shown as hav- Ying a -connectingrod .21fengaged with the crank 28 of the crank shaft-29 journalled,substantially, centrally across themi'd-length portion of the working cylinder. 5

The outer, free piston 2l is .shown as arched at 30in itsmid-length .portion to pass about the crankshaft-bearings 3| and the mid-portionof the-working cylinder is enlarged transversely at 32 te accommodate the: intermediate enlarged portion ofthe free; piston.

Gibs 33 on the enlarged or widened side `portions ofthe power piston,.operating in ways 34 in the Ysides of-the working cylinder,-hold this vfree piston against turning and may serve to limit the extent of its stroke.

vThe compression coupling between the two pistons'is created by providing a check valved suctioninlet-35,.Fig. 1, in the crank caseenlargement of Hthe-working cylinder and by-equipping thecompressor piston 22 with an inlet'valve 35, Fig. openingyfromthe crank chamber side `of the piston up into the compressor space 31 between the heads'V of the two pistons.

Air compressed between the pistons is 4.additionally used for scavenging andcharging purposes by passing the samejthrough an outlet valve .38, Figj2, opening'V downwardly in the headof Vthe compressor pistony into'a passage or chamber 39 inthis piston ported at 40 to register at proper times A'with'an upwardly inclined through port 4l. in the side of the-power piston and which latterport, at proper time`s,-registers with the lower end of a bypass42 in the side of the working cylinder opening at its Yuppe'rend to a position above .the power-piston.

Structuraldetails .of the inlet and outlet .valves 36, 3'8', are illustrated inFigs. Sto 7. In each case the valving is eieoted by a series of exible strips 43 in "the inlet` valve and 44 in the outlet'l valve, confined free .to bendand Slide between slotted plugs. 45, 46 'and 41,48.

At ytlf-einlet valve, Figs.3.and '7, the base plug 45 is cross slotted at 49 and flat on top and the upper plugiyhascross slots 50 oiset fromthe slots in the base and is concaved at 5l at its -under side to permit-upward lexure ofthe valve strips 43. The upperl plug is shown as screwthreaded into the .head'of the piston to secure Athe .valve unit in-place and the two elements'll, Mi,k between `which the valve strips are loosely -connedma-yfbe keyed or rigidly connected together so that the slots in the two'will stand in the alternating relation shown in'Fig. 3.

the explosive mixture.

The outlet valve 38, Figs. 3 and 6, is generally similar in construction, with slots 52 in the lower disc or base portion oifset from the slots 53 in the upper screw plug 48, but in this case the lower face of the upper member isflat and the upper face of the lower member is concaved as at 54, to admit downward exure of the valve strips 44.

With downward movement of the compressor piston the loose Valve strips 43 will bow upwardly due to the tendency to create a vacuum in compression space 31, causing air from the crank chamber to pass up into the compression space 31 between theH two pistons and with registry of ports or passages 40, 4l, 42, and uncovering of the upper end of bypass 42, air compressed in said chamber will bow the valve strips 44 downwardly to permit passage into the combustion chamber in the head of the working cylinder above the power piston.

A spark plug 55, Fig. l, is shown set in the head of the working cylinder and this cylinder is Ashown in Fig. 2 as having a fuel injection inlet 56 in one side and an exhaust port 51 in the opposite side, the latter located to be uncovered by the power piston at proper times in the outstroke of the same.

Working cylinder through a connection 6| and inlet 62 into the chamber 63 beneath the hammer end of the power piston. Flutes 64 in the hammer extension 23 may serve for passing this air to the drill steel and such utes may be used additionally or alone, as the case may be, for imparting rotation to the drill holder.

Referring to the diagrammatic views for a more complete understanding of the operation, Fig. 10 illustrates the parts substantially at completion of the compression stroke and firing of In this position all ports and valves are closed, with an air cushion trapped in the compression chamber 31 between the heads of the two pistons.

Fig. 11 illustrates the outstroke of both pistons, the compressor piston driven by the air spring confined between the two pistons. In this stroke air taken into the crank case on the previous suction stroke of the inner, compressor piston is being drawn into the compressor space 31. This view also illustrates the position of parts immediately before impact.

Fig. 12 illustrates the approximate position of parts at or immediately after impact, with the power piston opening the upper end of the bypass passage 42 to admit scavenging air from the compression chamber 31 to the explosion chamber, the inner piston port 4E! at such time registering with the outer piston port 4I and the latter registering with lower end of bypass 42. Also at such time the power piston has uncovered exhaust port 51. The cylinder at this time may rise, aiding in the quick uncovering of bypass and exhaust port. i

Fig. 13 illustrates the follow through of the hammer piston and the cylinder starting to drop on the rebound of the hammer piston. At such time the exhaust -port is entirely open but the compressed scavenging air is cut o by further outward travel of the compressor piston in the power piston sufficient to carry port 40 in this piston out of register with port 4| in the power piston. With ow of scavenging air thus shut off, air from the crank chamber is admitted by inlet valve 36 into compression chamber 31 between the pistons for compression.

Fig. 14 illustrates rebound of the hammer piston and commencement of the compression stroke of both pistons, all Valving passages or ports being closed in this portion of the cycle.

Fig. 15 illustrates the relation of parts substantially at the moment of fuel injection at 56 and during continuation of compression of the air trapped in the explosion chamber and the air cushion trapped between the power and compressor pistons.

Full automatic lubricationV of al1 operating parts is effected in the illustration by constructing the lower end of the power piston as a well or reservoir 65 for lubricant, it being noted that the open sides 36 of this piston provide access of such oil to the walls of thecontaining cylinder. This splash system of lubrication aids in cooling the parts. Lubricant in the splash well may be replenished through the crank case air inlet at 35 or a special oil filler opening may be provided in the side of the crank case portion of the working cylinder, normally closed by a suitable plug as indicated at 66 in Fig. 1. A ywheel and the rotary elements of a magneto, fuel injection pump and any other required accessory elements may be mounted on the exposed end or ends of the crank shaft.

The Amounting of the crank shaft directly across the mid-portion of the working cylinder and the arching of the mid-portion of the hammer piston about the crank shaft provides a particularly compact close-dirmensioned structure which can be light and small enough for ready portability and easy handling. The parts are of rugged design and the only part subjected to ham-mer action, that is, the power piston, operates freely in the working cylinder, disconnected from the crank shaft except for the indirect air cushion coupling with the compressor piston.

While referred to herein generally as a power hammer, it will be realized that the invention is applicable to mechanisms broadly of combined reciprocating and rotary type here indicated.

What is claimed is:

1. A power hammer comprising a working cylinder, a crank shaft journalled across the midportion of said cylinder, a power piston operating -in said cylinder and arched in its mid-portion about said crank shaft, a compressor piston operating in said power piston and connected with said crank shaft, cooperative means on said working cylinder, power piston and compressor piston for effecting intake and compression of air between said pistons and transfer of air so compressed between the pistons into the working cylinder above the power piston, said means including intake and outlet valves in the compressor piston, a passage from the outlet valve through the side ofthe compressor piston, a through port in the power piston to register with the end of said passage in the compressor piston and a passage in the working cylinder ported at one end to register with said through passage and ported at the opposite end to open into the working cylinder above the power piston.

2. A power hammer comprising a working cylinder, a crank shaft journalled across the 'mid-portion of said cylinder, a power piston operating in said cylinder and arched in its mid- 'portion about saidV crank shaft, a compressor ceses-sea workingI cylindersand-theearohed mideportionzaoi* said* power" piston-| having# slidinglyv4`r engaging keying'elementss' 3i A4v power hammer comprising* a"L working cylinder; arv` crank-f shaftv join-nailedacrosslthe mid=portion-of said" cylindr afpower piston' operating' 'in' said cylinder and arched in its: mid-portion" about said crank"sl''aft; al compressorV piston operating in'esaid A:power piston'- and con-- nected with said/crankshaft and Acooperative means on said Iworking cylinder, power piston and compressor piston for*eiec-tingv intake and compression of air betweensaid-'f vpistons l' and transfer of air so compressed between thel'p'isitons into 4 the lworking cylinder? above/the power` piston" operating in said cylinder'Y and' slotted in its-mid-portion topassithelcrankshaft, means slidinglyj-keyin'g -said A*free* piston in non-rotative relation'- in the-V cylinder, a compressor piston' operatingf in said power piston and?I connected with said crankfshaft-'and'means A"eorijrJi-ntly con@ trolled Ibysaid-'compressor andi -power pistons-for maintaining) an'v airTA cushion coupling between' thev headsof'saidpistons fandlfrpassingairl so compressed fromM said@ air cushion --into theV mer'and Vcomprising aeworking cylinder, avr-crank-I shaft -1 journalled trax-is-versely across f the`-`r mid-V portionofsaid'working'cylinder affree power piston operating' in said-"fcyli'nderL and slotted` in itsmid-portion topassv` the crank shaftg meansz slidingly keyingf said free *piston in' non`rotativer relation in! the cylindc-ir,l al 'compressori piston operating in said power piston and connected' with said cra-nk shaft and' means conioi-r`itlfy-'con-y trolled byy sa-idcomp'ressor and power pist-ous for maintainingan-'aircushion coupling `between the' heads' of lrsaid pistons and" for-'passing' airlso compressed 'from' said yair cushionlintf'a' the fwor-kl ingY cylinderfabovefthe freeipowenpis'tonf. working cylinder' havingffuel' injectioir andeX- haust portsy controlled' by said power' piston;

61" Incpercussiveapparatus lhavinga-power' generati'ng' agency` of fthe internat combustion engine type, a'- workingAt cylinder; thev upper i' portion lof which'. constitutes ianexplosion" chamber; thefcentralportionofssaidicylindersihaving a crank shaft journalled across it, a power piston, the upper portion of which)operateszinsaidexplosion chamber. and by. means of an arched ysection in its midportion surrounding 'said crank shaft is connected to a lower guide piston movable in the lower portion of` said* working@cylinderv structure, a strikingiimember projectingiaxially downwardly from said-guide piston to providewan unobstructed freefhammering action, and anfiair compressor pistoni-operating?within'igsaidippwerpistone'ad conneeted'withfsaidacrarikshaft;L

'7 In permissiveY apparat-,iishavingarpoweegem eratin agency ofr'tneiinternal -combustorrteng-ine. type, a@ working? cylinders'. thetzupperf.-portions of' which constitutesian explosioir-chamberfthezcene tral portinfof:saidcylinder;havingfafrcrankshaft journalled across it; a?, power? pistoni-1 the supper portion of which' operatesfinfsaidexplosiortchama-` ber andb'ymeans of*fanzarched'lsectiorrinzits"mide portion surrounding saidf crank-'shaft iS-'conneotdi to a'=lower guide pistonmovable-inrthelwerfportionfof` said :workingv cylinder Astructure,ea@striking memberv proj ectir'igfa-X-iallydownwardly:fiomfsaid guide piston; to' provide# an unobstructed" fiee hammering action, anaireompressor piston l013'-- erating `within'- said 'powerf piston and"i connected" with sa-id crankl shaft, intake and"`dischargeeair valves located'in the h'eadof said `airfcompressor piston; air dischargeportslocatedinthe-'Walisl:of

inci'dvat critical-points: in nthe vmo'venient off-"said'f pistons to admit scavengingean'd Yfuel'mixirgairY into the explosion chamber' of thework'ing cylin# der abovev the powerV piston, through asw'itch'backvv portinginy the' wall of -said cylinder:

8.1 Inpercussive apparatus fhavingafpower'igem erating Yagency of the"internal"combustionengine type; a workingcylinderi the;upper'"portion` of which constitutes'fan explosionchamber, th`e"cen"= tral portionpof said cylinder having arci-ank shaft' iournalled' across it', a" power" piston; the 'upper portion of which voperates irr'saidexplosionphamiber andby means 'of l'anar'chedit'section"irrits;rnid portionsurrounding said 'crank'shaftis"connecte'dv to aloweriguide piston'movablin'thel'werp'ore tionof said working' cylinderstructure, astriking memberv projecting axially'downwardly"from said guide'pistonv to provide an unobstructed'fee hammering action, an air compressor piston operatir'lg withinsaid power piston and connected Witl'i said crankshaft; intake and."'discharge air valves 1ocated in the headof said aircompressor piston', air discharge ports located in. the walls Y ofsaid compressor. and power pistons, toadmitlscavengring andfuel mixingv air. into. the .explosionchambei: of 1 the` working cylinder aboveitli'epower. pistonr. through aswitch .back yporting .in the wall of saidworkingcylinden said. cylinder'havingfa fuel" injection lport leading directly into the combustion chamber, andan exhaust port covered-fand une covered bythe workingfpistonat different Stages inthe stroke ofthe-same;

9. In percussivefapparatusehavinga/ power-,genev erating: agency of the internal,combustionffenginer type,A a rworking cylinder,A the upper-portion of*V whichirconstitutes arr explosion chambers` the cene trai portionof saidcylinder havinga crankshaft journalled across it, a powerspiston; i ,their upper portionofY which operates. in said explosion cham-'- ber and loi/,means :of anarched sectioniniitsnnid-- portion surrounding said oranlcshaftfisconnected to :a lower :guideapiston .movable-ini.theclowen-por.L tion of: said workingicylindenstructure; aistrikingf member: projecting axially downwardly-from said crank shaft; i intake: andi discharge: airrvalvest'loie cated finthe'. head of saidifairf compressor piston;

air discharge :ports-r locatedrin the? wallsf of Afsaid..

compressor.'fandfpowerpistonsg'.timed-to coincide atzcritical .pointsain;theimovement fofsaidpistonsa` toi-'admit scavengingerand'ffuelwinixing air;intothel explosion, ohambenzof"thexfworkingccylinderabovef thefpower pistonithrough" a switch;backpoi-'ting` inzthe-rwallof 'f'said-lworking cylinder; sazidpcyli'nder-11p having a fuel injection port leading directly into the combustion chamber and an exhaust port covered and uncovered by the working piston at different stages in the stroke of the same, the crank containing portion of said working cylinder and the arched mid-portion of said power piston having slidingly engaging keying elements.

10. In percussive apparatus having a power generating agency of the internal combustion engine type, a working cylinder, the upper portion of which constitutes an explosion chamber, the central portion of said cylinder having a crank shaft journalled across it, a power piston, the upper portion of which operates in said explosion chamber and by means of an arched section in its mid-portion surrounding said crank shaft is connected to a lower guide piston mov- .able in the lower portion of said working cylinder structure, a striking member projecting axially downwardly from said guide piston to provide an unobstructed free hammering action, an air compressor piston operating within said power piston and connected with said crank shaft, intake and discharge air valves located in the head of said air compressor piston, air discharge ports located in the walls of said compressor and power pistons to admit scavenging and fuel mixing air into the explosion chamber of the working cylinder above the power piston, through a switch back porting in the wall of said working cylinder, said working cylinder having a fuel injection port leading directly into the combustion chamber, an exhaust port covered and uncovered by the working piston at different stages in the stroke of the same, said power piston having a lubricant well at the inner lower end of the same for effective splash lubrication of the parts described, the arched mid-portions of said power piston providing access of lubricant to the 'walls of said working cylinder.

11. In percussive apparatus having a power generating agency of the internal combustion engine type, a working cylinder, the upper portion of which constitutes an explosion chamber, the central portion of said cylinder having a crank shaft journalled across it, a power piston, the upper portion of which operates in said explosion chamber and by means of an arched section in its mid-portion surrounding said crank shaft is connected to a lower guide piston movable in the lower portion of the working cylinder structure, a striking member projecting axially downwardly from said guide piston to provide an unobstructed free hammering action, an air compressor piston operating within said power piston and connected with said crank shaft, intake and discharge air valves located in the head of said air compressor piston and air discharge ports located in the walls of said compressor and power pistons, timed to coincide at critical points in the movement of said pistons to admit scavenging and fuel mixing air into the explosion chamber of the working cylinder above the power piston, through a switch back porting in the wall of said cylinder, said power piston and compressor piston having means for s'upplying a flow of jetting air to the head at the front end of the working cylinder.

12. In percussive apparatus having a power generating agency of the internal combustion engine type, a working cylinder, the upper portion of which constitutes an explosion chamber, the central portion of said cylinder having a crank shaft journalled across it, a power piston,

the upper portion of which operates in said explosion chamber and by means of an arched section in its mid-portion surrounding said crank shaft is connected to a lower guide piston movable in the lower portion of said working cylinder structure, a Striking member projecting axially downwardly from said crank shaft, intake and discharge air valves located in the head of said air compressor piston, air discharge ports located in the walls of said compressor and power pistons, timed to coincide at critical points in the movement of said pistons to admit scavenging and fuel mixing air into the explosion chamber of the working cylinder above the power piston, through a switch back porting in the walls of said working cylinder, said working cylinder having a fuel injection port leading directly into the combustion chamber, an exhaust port covered and uncovered by the working piston at diiferent stages in the stroke of the same,

the crank containing portion of said working cylinder and the arched mid-portion of said power piston having slidingly engaging keying elements and means conjointly controlled by said compressor and power pistons for maintaining an expansible air cushion coupling between the heads of said pistons.

13. In percussive apparatus having a power generating agency of the internal combustion engine type, a working cylinder, the upper portion of which constitutes an explosion chamber, the central portion of said cylinder having a crank shaft journalled across it, a power piston, the upper portion of which operates in said explosion chamber and by means of an arched section in its mid-portion surrounding said crank shaft is connected to a lower guide piston movable in the lower portion of said working cylinder structure, a striking member projecting axially downwardly from said crank shaft, intake and discharge air valves located in the head of said air compressor piston, air discharge ports located in the walls of said compressor and power pistons, timed to coincide at critical points in the movement of said pistons to admit scavenging and fuel mixing air into the explosion chamber of the working cylinder above the power piston, through a switch back porting in the wall of said working cylinder, said working cylinder having a fuel injection port leading directly into the combustion chamber, an exhaust port covered and uncovered by the working piston at different stages in the stroke of the same, the crank containing portion of said working cylinder and the arched mid-portion of said power piston having slidingly engaging keying elements and means conjointly controlled by said cornpressor and power pistons for maintaining an expansible air cushion coupling between the heads of said piston and for passing air so compressed from said air cushion into the working cylinder above the free power piston, said working cylinder having a fuel injection port leading directly into the combustion chamber and an exhaust port controlled by said power piston.

CHARLES A. HIRSCHBERG.

REFERENCES CITED YThe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,058,268 I ySCOLZ) Apr. 8, 1913 1,340,223 H0128 May 18, 1920 

